Major oxides provide valuable information about the composition, origin, and properties of rocks and regolith. Analysing major oxides contributes significantly to understanding the nature of geological materials and processes (i.e. physical and chemical weathering) – with potential applications in resource exploration, engineering, environmental assessments, agriculture, and other fields. Traditionally most measurements of oxide concentrations are obtained by laboratory assay, often using X-ray fluorescence, on rock or regolith samples. To expand beyond the point measurements of the geochemical data, we have used a machine learning approach to produce seamless national scale grids for each of the major oxides. This approach builds predictive models by learning relationships between the site measurements of an oxide concentration (sourced from Geoscience Australia’s OZCHEM database and selected sites from state survey databases) and a comprehensive library of covariates (features). These covariates include: terrain derivatives; climate surfaces; geological maps; gamma-ray radiometric, magnetic, and gravity grids; and satellite imagery. This approach is used to derive national predictions for 10 major oxide concentrations at the resolution of the covariates (nominally 80 m). The models include the oxides of silicon (SiO2), aluminium (Al2O3), iron (Fe2O3tot), calcium (CaO), magnesium (MgO), manganese (MnO), potassium (K2O), sodium (Na2O), titanium (TiO2), and phosphorus (P2O5). The grids of oxide concentrations provided include the median of multiple models run as the prediction, and lower and upper (5th and 95th) percentiles as measures of the prediction’s uncertainty. Higher uncertainties correlate with greater spreads of model values. Differences in the features used in the model compared with the full feature space covering the entire continent are captured in the ‘covariate shift’ map. High values in the shift model can indicate higher potential uncertainty or unreliability of the model prediction. Users therefore need to be mindful, when interpreting this dataset, of the uncertainties shown by the 5th-95th percentiles, and high values in the covariate shift map. Details of the modelling approach, model uncertainties and datasets are describe in an attached word document “Model approach uncertainties”. This work is part of Geoscience Australia’s Exploring for the Future program that provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. These data are published with the permission of the CEO, Geoscience Australia.

<div>The soil gas database table contains publicly available results from Geoscience Australia's organic geochemistry (ORGCHEM) schema and supporting oracle databases for gas analyses undertaken by Geoscience Australia's laboratory on soil samples taken from shallow (down to 1 m below the surface) percussion holes. Data includes the percussion hole field site location, sample depth, analytical methods and other relevant metadata, as well as the molecular and isotopic compositions of the soil gas with air included in the reported results. Acquisition of the molecular compounds are by gas chromatography (GC) and the isotopic ratios by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The concentrations of argon (Ar), carbon dioxide (CO₂), nitrogen (N₂) and oxygen (O₂) are given in mole percent (mol%). The concentrations of carbon monoxide (CO), helium (He), hydrogen (H₂) and methane (C₁, CH₄) are given in parts per million (ppm). Compound concentrations that are below detection limit (BDL) are reported as the value -99999. The stable carbon (¹³C/¹²C) and nitrogen (¹⁵N/¹⁴N) isotopic ratios are presented in parts per mil (‰) and in delta notation as δ¹³C and δ¹⁵N, respectively.</div><div><br></div><div>Determining the individual sources and migration pathways of the components of natural gases found in the near surface are useful in basin analysis with derived information being used to support exploration for energy resources (petroleum and hydrogen) and helium in Australian provinces. These data are collated from Geoscience Australia records with the results being delivered in the Soil Gas web services on the Geoscience Australia Data Discovery portal at https://portal.ga.gov.au which will be periodically updated.</div>

<b>Organic Geochemistry (ORGCHEM) Schema. Australian Source Rock and Fluid Atlas</b> The databases tables held within Geoscience Australia's Oracle Organic Geochemistry (ORGCHEM) Schema, together with other supporting Oracle databases (e.g., Borehole database (BOREHOLE), Australian Stratigraphic Units Database (ASUD), and the Reservoir, Facies and Shows (RESFACS) database), underpin the Australian Source Rock and Fluid Atlas web services and publications. These products provide information in an Australia-wide geological context on organic geochemistry, organic petrology and stable isotope data related primarily to sedimentary rocks and energy (petroleum and hydrogen) sample-based datasets used for the discovery and evaluation of sediment-hosted resources. The sample data provide the spatial distribution of source rocks and their derived petroleum fluids (natural gas and crude oil) taken from boreholes and field sites in onshore and offshore Australian provinces. Sample depth, stratigraphy, analytical methods, and other relevant metadata are also supplied with the analytical results. Sedimentary rocks that contain organic matter are referred to as source rocks (e.g., organic-rich shale, oil shale and coal) and the organic matter within the rock matrix that is insoluble in organic solvents is named kerogen. The data in the ORGCHEM schema are produced by a wide range of destructive analytical techniques conducted on samples submitted by industry under legislative requirements, as well as on samples collected by research projects undertaken by Geoscience Australia, state and territory geological organisations and scientific institutions including the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and universities. Data entered into the database tables are commonly sourced from both the basic and interpretive volumes of well completion reports (WCR) provided by the petroleum well operator to either the state and territory governments or, for offshore wells, to the Commonwealth Government under the Offshore Petroleum and Greenhouse Gas Storage Act (OPGGSA) 2006 and previous Petroleum (submerged Lands) Act (PSLA) 1967. Data are also sourced from analyses conducted by Geoscience Australia’s laboratory and its predecessor organisations, the Australian Geological Survey Organisation (AGSO) and the Bureau of Mineral Resources (BMR). Other open file data from company announcements and reports, scientific publications and university theses are captured. The ORGCHEM database was created in 1990 by the BMR in response to industry requests for organic geochemistry data, featuring pyrolysis, vitrinite reflectance and carbon isotopic data (Boreham, 1990). Funding from the Australian Petroleum Cooperative Research Centre (1991–2003) enabled the organic geochemical data to be made publicly available at no cost via the petroleum wells web page from 2002 and included BOREHOLE, ORGCHEM and the Reservoir, Facies and Shows (RESFACS) databases. Investment by the Australian Government in Geoscience Australia’s Exploring for the Future (EFTF) program facilitated technological upgrades and established the current web services (Edwards et al., 2020). The extensive scope of the ORGCHEM schema has led to the development of numerous database tables and web services tailored to visualise the various datasets related to sedimentary rocks, in particular source rocks, crude oils and natural gases within the petroleum systems framework. These web services offer pathways to access the wealth of information contained within the ORGCHEM schema. Web services that facilitate the characterisation of source rocks (and kerogen) comprise data generated from programmed pyrolysis (e.g., Hawk, Rock-Eval, Source Rock Analyser), pyrolysis-gas chromatography (Py-GC) and kinetics analyses, and organic petrological studies (e.g., quantitation of maceral groups and organoclasts, vitrinite reflectance measurements) using reflected light microscopy. Collectively, these data are used to establish the occurrence of source rocks and the post-burial thermal history of sedimentary basins to evaluate the potential for hydrocarbon generation. Other web services provide data to characterise source rock extracts (i.e., solvent extracted organic matter), fluid inclusions and petroleum (e.g., natural gas, crude oil, bitumen) through the reporting of their bulk properties (e.g., API gravity, elemental composition) and molecular composition using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Also reported are the stable isotope ratios of carbon, hydrogen, nitrogen, oxygen and sulfur using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) and noble gas isotope abundances using ultimate high-resolution variable multicollection mass spectrometry. The stable isotopes of carbon, oxygen and strontium are also reported for sedimentary rocks containing carbonate either within the mineral matrix or in cements. Interpretation of these data enables the characterisation of petroleum source rocks and identification of their derived petroleum fluids, which comprise two key elements of petroleum systems analysis. Understanding a fluid’s physical properties and molecular composition are prerequisites for field development. The composition of petroleum determines its economic value and hence why the concentration of hydrocarbons (methane, wet gases, light and heavy oil) and hydrogen, helium and argon are important relative to those of nitrogen, carbon dioxide and hydrogen sulfide for gases, and heterocyclic compounds (nitrogen, oxygen or sulfur) found in the asphaltene, resin and polar fractions of crude oils. The web services and tools in the Geoscience Australia Data Discovery Portal (https://portal.ga.gov.au/), and specifically in the Source Rock and Fluid Atlas Persona (https://portal.ga.gov.au/persona/sra), allow the users to search, filter and select data based on various criteria, such as basin, formation, sample type, analysis type, and specific geochemical parameters. The web map services (WMS) and web feature services (WFS) enable the user to download data in a variety of formats (csv, Json, kml and shape file). The Source Rock and Fluid Atlas supports national resource assessments. The focus of the atlas is on the exploration and development of energy resources (i.e., petroleum and hydrogen) and the evaluation of resource commodities (i.e., helium and graphite). Some data held in the ORGCHEM tables are used for enhanced oil recovery and carbon capture, storage and utilisation projects. The objective of the atlas is to empower people to deliver Earth science excellence through data and digital capability. It benefits users who are interested in the exploration and development of Australia's energy resources by: • Providing a comprehensive and reliable source of information on the organic geochemistry of Australian source rocks • Enhancing the understanding of the spatial distribution, quality, and maturity of petroleum source rocks. • Facilitating the mapping of total petroleum and hydrogen systems and the assessment of the petroleum and hydrogen resource potential and prospectivity of Australian basins. • Facilitating the mapping of gases (e.g., methane, helium, carbon dioxide) within the geosphere as part of the transition to clean energy. • Enabling the integration and comparison of data from diverse sources and various acquisition methods, such as geological, geochemical, geophysical and geospatial data. • Providing data for integration into enhanced oil recovery and carbon capture, storage and utilisation projects. • Improving the accessibility and usability of data through user-friendly and interactive web-based interfaces. • Promoting the dissemination and sharing of data among Government, industry and community stakeholders. <b>References</b> Australian Petroleum Cooperative Research Centre (APCRC) 1991-2003. Australian Petroleum CRC (1991 - 2003), viewed 6 May 2024, https://www.eoas.info/bib/ASBS00862.htm and https://www.eoas.info/biogs/A001918b.htm#pub-resources Boreham, C. 1990. ORGCHEM Organic geochemical database. BMR Research Newsletter 13. Record 13:10-10. Geoscience Australia, Canberra. https://pid.geoscience.gov.au/dataset/ga/90326 Edwards, D.S., MacFarlane, S., Grosjean, E., Buckler, T., Boreham, C.J., Henson, P., Cherukoori, R., Tracey-Patte, T., van der Wielen, S.E., Ray, J., Raymond, O. 2020. Australian source rocks, fluids and petroleum systems – a new integrated geoscience data discovery portal for maximising data potential. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/133751. <b>Citation</b> Edwards, D., Buckler, T. 2024. Organic Geochemistry (ORGCHEM) Schema. Australian Source Rock and Fluid Atlas. Geoscience Australia, Canberra. https://pid.geoscience.gov.au/dataset/ga/149422

<div>The pyrolysis-gas chromatography database table contains publicly available results from Geoscience Australia's organic geochemistry (ORGCHEM) database and supporting oracle databases for open system pyrolysis-gas chromatography (pyrolysis-GC) analyses performed on either source rocks or kerogen samples taken from boreholes and field sites. Sedimentary rocks that contain organic matter are referred to as source rocks (e.g., organic-rich shale, oil shale and coal) and the organic matter within the rock matrix that is insoluble in organic solvents is named kerogen. The analyses are undertaken by various laboratories in service and exploration companies using a range of instruments. Data includes the borehole or field site location, sample depth, stratigraphy, analytical methods, other relevant metadata, and the molecular composition of the pyrolysates. The concentrations of the aliphatic hydrocarbon, aromatic hydrocarbon and organic sulfur compounds are given in several units of measure [e.g., percent (resolved compounds) in the S2 peak (wt% S2), milligrams per gram of rock (mg/g rock), micrograms per gram of kerogen (mg/g kerogen) etc.].</div><div><br></div><div>These data are used to determine the organic richness, kerogen type and thermal maturity of source rocks in sedimentary basins. The results are used as input parameters in basin analysis and petroleum systems modelling to evaluate the potential for hydrocarbon generation in a sedimentary basin. These data are collated from destructive analysis reports (DARs), well completion reports (WCRs) and literature. The data are delivered in the Source Rock Pyrolysis-Gas Chromatography web services on the Geoscience Australia Data Discovery Portal at https://portal.ga.gov.au which will be periodically updated.</div><div><br></div>

<div>The fluid inclusion stratigraphy database table contains publicly available results from Geoscience Australia's organic geochemistry (ORGCHEM) schema and supporting oracle databases for Fluid Inclusion Stratigraphy (FIS) analyses performed by FIT, a Schlumberger Company (and predecessors), on fluid inclusions in rock samples taken from boreholes. Data includes the borehole location, sample depth, stratigraphy, analytical methods and other relevant metadata, as well as the mass spectrometry results presented as atomic mass units (amu) from 2 to 180 in parts per million (ppm) electron volts.</div><div> Fluid inclusions (FI) are microscopic samples of fluids trapped within minerals in the rock matrix and cementation phases. Hence, these FIS data record the bulk volatile chemistry of the fluid inclusions (i.e., water, gas, and/or oil) present in the rock sample and determine the relative abundance of the trapped compounds (e.g., in amu order, hydrogen, helium, methane, ethane, carbon dioxide, higher molecular weight aliphatic and aromatic hydrocarbons, and heterocyclic compounds containing nitrogen, oxygen or sulfur). The FI composition can be used to identify the presence of organic- (i.e., biogenic or thermogenic) and inorganic-sourced gases. These data provide information about fluid preservation, migration pathways and are used to evaluate the potential for hydrocarbon (i.e. dry gas, wet gas, oil) and non-hydrocarbon (e.g., hydrogen, helium) resources in a basin. These data are collated from Geoscience Australia records, destructive analysis reports (DARs) and well completion reports (WCRs), with the results being delivered in the Fluid Inclusion Stratigraphy (FIS) web services on the Geoscience Australia Data Discovery Portal at https://portal.ga.gov.au which will be periodically updated.</div>

<div>The pyrolysis-reflectance tie database table contains publicly available results from Geoscience Australia's organic geochemistry (ORGCHEM) schema and supporting oracle databases, which combine key properties related to thermal maturity. These data are typically used as input parameters in basin analysis and petroleum systems modelling to assist with the discovery and evaluation of sediment-hosted energy resources. The programmed pyrolysis analyses and the maceral reflectance analyses undertaken using reflected light microscopy are conducted on rock samples, either as cores, cuttings or rock chips, taken from boreholes and field sites in Australian sedimentary basins. The full datasets are available in the pyrolysis, vitrinite reflectance, maceral reflectance and organoclast maturity web services. These analyses are performed by various laboratories in service and exploration companies, Australian government institutions and universities using a range of instruments.</div><div><br></div><div>These data are collated from destructive analysis reports (DARs), well completion reports (WCRs), and literature. The data are delivered in the Combined Pyrolysis and Vitrinite Reflectance web services on the Geoscience Australia Data Discovery Portal at https://portal.ga.gov.au which will be periodically updated.</div>

<div>This guide and template details data requirements for submission of mineral deposit geochemical data to the Critical Minerals in Ores (CMiO) database, hosted by Geoscience Australia, in partnership with the United States Geological Survey and the Geological Survey of Canada. The CMiO database is designed to capture multielement geochemical data from a wide variety of critical mineral-bearing deposits around the world. Samples included within this database must be well-characterized and come from localities that have been sufficiently studied to have a reasonable constraint on their deposit type and environment of formation. As such, only samples analysed by modern geochemical methods, and with certain minimum metadata attribution, can be accepted. Data that is submitted to the CMiO database will also be published via the Geoscience Australia Portal (portal.ga.gov.au) and Critical Minerals Mapping Initiative Portal (https://portal.ga.gov.au/persona/cmmi).&nbsp;</div><div><br></div>

<div><strong>Output Type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>Groundwater geochemistry is an important and often under-appreciated medium to understand geology below surface and is a valuable tool as part of a regional mineral exploration program. This study presents an assessment of hydrogeochemical results from the Curnamona and Mundi region with respect to their insights into mineral prospectivity and characterisation of groundwater baselines. The work is a collaboration with the Mineral Exploration Cooperative Research Centre (MinEx CRC), the Geological Survey of New South Wales and the Geological Survey of South Australia as part of Geoscience Australia’s Exploring for the Future program. It combines new and legacy groundwater chemistry from 297 samples to identify multiple elevated multi-element anomalies (Ag, Pb, Cd) and signatures of sulfide mineralisation (d34S and sulfur excess), which are interpreted as potential features from subsurface Broken Hill Type mineralisation (Pb-Zn-Ag). Additional multi-element anomalies (Cu, Mo, Co, Au) may be attributable to Cu-Au, Cu-Mo and Au mineralisation. We then apply hierarchical cluster analysis to understand sample hydrostratigraphy and characterise robust hydrogeochemical baselines for the major aquifer systems in the region. This reveals that the majority of anomalies are restricted to groundwaters derived from basement fractured rock aquifer systems, with a couple anomalies observed in the Lake Eyre Basin cover, which helps narrow the search-space for future groundwater-based mineral exploration in this region (to prioritise these aquifers and anomalies). In addition, we demonstrate the capability of these local hydrogeochemical baselines to support more sensitive resolution of hydrogeochemical anomalies relating to mineralisation, as well as reveal hydrogeological processes such as mixing.</div><div><br></div><div><strong>Citation: </strong>Reid, N., Schroder, I., Thorne, R., Folkes, C., Hore, S., Eastlake, M., Petts, A., Evans, T., Fabris, A., Pinchand, T., Henne A., & Palombi, B.R., 2024. Hydrogeochemistry of the Curnamona and Mundi region. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts. Geoscience Australia, Canberra. https://doi.org/10.26186/149509</div>

<div>This study was commissioned by Geoscience Australia (GA) as part of the Exploring for the Future program to produce a report on the organic petrology for rock samples from drill holes of the Birrindudu Basin, Northern Territory, Australia. A suite of 130 drill core samples from 6 drill holes was analysed using standard organic petrological methods to identify the types of organic matter present, assess their relative abundances and determine the levels of thermal maturity attained by the sedimentary organic matter using the reflectance of organoclasts present. </div>

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short abstract: </strong>Australian sediment-hosted mineral systems play a crucial role in providing base metals and critical minerals essential for the global low-carbon economy. The Georgina Basin has the key components for forming and preserving a sediment-hosted Zn-Pb mineral system, but historically has been considered ‘cover’ to deeper, more prospective Proterozoic basement rocks. Thus, the basin has remained relatively under-explored, with many questions yet to be resolved on its sediment-hosted Zn-Pb mineral system and prospectivity for Zn-Pb. Utilising new whole-rock and isotope geochemistry of the Georgina Basin from recently drilled holes in the Northern Territory, we demonstrate the sensitivity of local redox boundaries to detect regional mineralisation. Two geochemically enriched zones have been identified and interpreted as redox interfaces which have trapped and concentrated metals from the surrounding basin, a ‘supergene zone’ and a ‘water intercept zone’. The ‘supergene zone’ is a paleo water table horizon, while the ‘water intercept zone’ is an active redox front at the uppermost part of the Cambrian Limestone Aquifer. The enrichment of these redox zones is consistent across multiple drill holes, reaching up to 395 ppm Pb and 1550 ppm Zn. Additionally, the Pb isotopes of high-Pb and sulfidic intervals have a highly radiogenic character (206Pb/204Pb ~22.0–23.0) that is diagnostic of Georgina Basin’s Mississippi Valley-type Zn-Pb mineralisation. Taken together, these results suggest there may be buried mineralisation in this part of the Georgina Basin, as well as highlight the potential of these redox interfaces as a regional reconnaissance target for exploration.</div><div><br></div><div><strong>Citation: </strong>Schroder I.F., Huston D. & de Caritat P., 2024. The geochemistry of redox interfaces for insights into Zn-Pb prospectivity in the Georgina Basin. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149116 </div>